Excuse me for being such a n00b, but why does a standard gameport (to cite the example that brought the question to mind) have so many +5V and GND source pins? Couldn’t you just use one +5V and 1 GND and then have more pins for I/O?
Redundancy, I’d say. If one goes down, the entire thing still works. I’ll look into it, though.
Sparks
Orborde,
There is a long history on the joystick ports going back to Atari, Commodore and other stand alone games. Originally games could have two simple joysticks, i.e. no pots just switches in the four quadrants which gave you eight possible direction commands. Other games provided four pads for more people to play and those two set the standards for game interface. It was easier to wire two ports to the same connector if there were more than one 5 volt pin. When manufacturers started writing software for PC and making interfaces they decided to use what was available since in many cases they also made the stand alone games. As games and joysticks progressed, manufacturers had to use what was already in place to be competitive. The OI port only uses one 5 volt pin so that it can have other device I/O on the now free pins. Modern simple joysticks only use pin 1 as 5 volts, leaving the others not connected in the joystick.
I like that explaination better. Thanks Al!
Sparks